Arrangement for separation of suspended or emulsified material from aliquid

ABSTRACT

The present invention concerns a method of separating suspended or emulsified material from a liquid during its flow in at least one channel and also an apparatus for performing this method. It is found that the separation effect is highly increased when one or more channel walls are moving in their own longitudinal direction and the longitudinal direction of the channel.

United States Patent 1 Olgard et a1.

ARRANGEMENT FOR SEPARATION OF SUSPENDED 0R EMULSIFIED MATERIAL FROM A LIQUID Inventors: Gunner Olgard, Vikgatan 3 c,

Nynashamn; Ake Jernqvlst, Bygglovsgrand 15, Lund, both of Sweden Filed: May 19, 1971 Appl. No.: 144,985

Related U.S. Application Data Continuation-in-part of Ser. No. 797,452, Feb. 7, 1969, abandoned.

U.S. Cl 210/73, 210/83, 210/322,

210/526, 210/532 Int. Cl B0ld 2l/00 Field of Search 210/63, 73, 83, 84,

[ July 24, 1973 [56] References Cited UNITED STATES PATENTS 2,861,688 11/1958 Harmsm. 210/83 X 2,314,542 3/1943 Kern 210/526 X 415,314 11/1889 Singer et a1... 210/526 X 1,538,742 5/1925 Price 210/329 2,214,248 9/1940 Hawler 210/532 Primary Examiner-John Adee Attorney-Darby & Darby [57] ABSTRACT The present invention concerns a method of separating suspended or emulsified material from a liquid during its flow in at least one channel and also an apparatus for performing this method. It is found that the separation effect is highly increased when one or more channel walls are moving in their own longitudinal direction and the longitudinal direction of the channel.

16 Claims, 15 Drawing Figures PATENIED JUL 2 4 I975 saw as m 5 ARRANGEMENT FOR SEPARATION OF SUSPENDED OR EMULSIFIED MATERIAL FROM A LIQUID This application is a continuation-in-part of the copending application Ser. No. 797,452 filed Feb. 7, I969 by the present inventors and now abandoned.

In industry, separation primarily is carried out by sedimentation, centrifuging, by methods applying cyclones, precipitators, and by filtering. ()f said methods only the two lastmentioned ones are independent of the relation between the density of the material separated and the density of the liquid. If the difference in density of the separated material in relation to the liquid is small, the method of flotation can be applied which is a form of sedimentation.

In spite of the great number of different separation methods available, there still is a lack of methods and apparatus adapted for use in certain operations. This applies, for example, to waste water technology, particularly in the case of industrial waste water, but similar problems exist also in the chemical-technical and pharmaceutical industries.

This invention offers a solution of the aforesaid problems. It is directed to a method for performing separation of suspended or emulsified material from a liquid by utilizing the effect known per se, that suspended or emulsified material included in a liquid with speed gradients travels toward zones in the liquid where the speed gradient is smaller or sufficiently small. The term sufficiently small in this context is to be understood to mean that the shearing stress field in the liquid caused by speed gradients does not affect the material particles from a separation point of view. The invention is also directed to an apparatus in which the separation according to the method can be carried out.

The method according to the invention is associated with a channel to which the suspension is supplied. The channel is arranged vertically or has in any events an angle to the horizontal. The suspension is supplied to the channel at its upper part and flows downwardly through the channel. Such a flow provides a known speed distribution in the channel giving a low speed gradient in acomparatively large and central part of the channel. The separation effect hereby obtained is low and is of no practicaluse for separation.

By the present invention, however, it is possible to govern the separation such that a highly satisfying separation is obtained. This is effected in such a way that the lowest value of the speed gradient is displaced and concentrated in'the direction towards one side of the channel by arranging at least one of the channel walls movable in its own longitudinal direction substantially parallel with the axis of the channel. This displacement is accomplished when one or several channel walls are moved with a different speed compared with the other channel walls.

The invention is described in greater detail in the following, with reference to the accompanying drawings, wherein:

FIGS. 1 to 7 illustrate the theory behind the present invention.

FIGS. 8 to 12 show in a schematical way principal Figures of different channel embodiments for performing the separation according to the invention,

FIG. 13 is a perspective view of a part of an apparatus for performing the separation according to the invention,

FIG. 14 illustrates in an upper plan view how a suspension inlet to an apparatus according to FIG. 13 can be arranged, and

FIG. 15 illustrates in an upper plan view how a suspension inlet and a clarified liquid outlet can be arranged in connection to an apparatus having channels as shown in FIG. 9.

Referring to FIGS. l7 of the accompanying draw ings, two opposite vertical channel walls have the reference numerals 1 and 2. The speed. of the channel wall 1 is referred to as v, and the speed of the channel wall 2 as v The average speed of the suspension entering the channel from above and flowing downwardly is referred to as v,,,. In a system of cooridnates v-x and dv/dx-x respectively positioned as shown on the drawings, the speed distribution v is shown with continuous lines and the speed gradient dv/dx is shown with dashed curve.

FIG. 1 shows the speed distribution and the speed gradient at laminar flow in a channel having the walls standing still, thus existing speed conditions at conventional flow in a channel. A speed gradient minimum is here lying in the centre of the channel and according to what has been stated above the particles in the suspension will travel towards the central part of the channel. Due to the fact that the speed gradient at the central part has low values (approximately zero), the particle migration is spread out over a comparaively large central area. The separation effect obtained is weak and of no practical use.

FIGS. 2-7 show as examples some different cases lying within the frame of the present invention. One or both of the shown channel walls has a movement in its own longitudinal direction and the longitudinal direction of the channel. By this movement a displacement of the minimum or the lowest value of the speed gradient towards one or the other channel wall is obtained. By suitable choice of the direction of movement as well as the speed for the channel walls the minimum or the lowest value of the speed gradient can be displaced as far as to one channel wall. This can be calculated by means of the flow equation which in the present case has the following solution v ='--6 [v (v, v )/2] x /a [6v,, (4v, 2v,)] x/a. The derivate, which is the speed gradient, is

Here is:

v,,, the average speed of the suspension,

at the distance between the channel walls,

v, the speed of the first channel wall,

v, the speed of the second channel wall, and

v the variable of the speed at a distance x from the first wall. I

From the derivate equation appears that the speed gradient is zero at one of the channel walls,'if this wall moves downwardly with a speed of 3/2v,,, and the other wall stands still.

FIG. 2 shows just such a case, wherein the wall I ismoving downwardly with the speed 3/2 v,,, and the wall 2 stands still. The speed gradient is here zero at the movable wall 1 and particle migration occurs in direction towards this wall.

FIG. 3 shows the conditions when the wall 1 is moving downwardly with a speed less than 3/2 v,, and the wall 2 is standing still. The speed gradient has here a zero value displaced towards the movable wall and the particles migrate towards this zero plane.

FIG. 4 illustrates the conditions when the wall 1 is moving downwardly with a speed greater than 3/2 v while the wall 2 is standing still. The speed gradient has here a minimum displaced towards the movable wall and the particles migrate towards this minimum plane, probably with greater effect compared with the case according to FIG. 3, since the speed gradient at minimum has a value apart from zero.

From the above-mentioned flow equations it can also be derived, that the speed gradient can be zero at a wall standing still, if the other wall is moving downwardly with the speed 3v This is illustrated in FIG. 5, where the wall 1 is standing still, while the wall 2 is moving downwardly with the speed 3 v,,,.

FIG. 6 illustrates the conditions when the wall 1, as in FIG. 5, is standing still, while the wall 2 is moving downwardly with a speed greater than 3 v,,,. The speed gradient here has a lowest absolute value displaced towards the wall standing still.

The flow equations give an infinite number of solutions for those cases when both walls are moving in the same or opposite directions, FIG. 7 illustrates one case, when the two walls are moving in opposite directions. The position for the minimum of the speed gradient is of course dependent on the values it the speeds v regard v In the case illustrated in FIG. 7 the speed gradient has been assumed to have its minimum positioned adjacent the wall moving downwardly.

In all cases according to FIGS. 2 to 7 a particle migration is obtained towards one side of the channel between the walls 1 and 2. Hereby the condition precedent for a practicable separation is obtained. By appropriate choice of wall speeds and direction of movement the separation can be governed such that is is accomplished with greatest efficiency in re gard to actual kind of suspension or emulsion.

The said particle migration occurs irrespective of whether the density of the particles differd much from the density of the liquid or only insignificantly or not at all. Particularly when great density difference exists it can be appropriate to arrange the channel inclined relative to the horizontal plane, since in this case by suitable choice of wall movements an additional force promoting separation towards the lower wall of the channel is obtained due to the gravitation.

FIGS. 8 to 12 show schematically examples of different embodiments of channels for performing a separation according to the invention.

The channel shown in FIG. 8 comprises two movably mounted opposite walls, which are formed by endless belts 3 and 4 drawn about upper rolls 5 and 6, respectively, and lower rolls 7 and 8, respectively. At the lower end of the channel, between the lower rolls, a partition wall 9 is mounted. The belts 3 and 4, as shown, move in opposite directions and at different speeds v, and v,, respectively. The inlet of liquid is schematically shown arranged at the upper end of the channel and designated by T. The thickened solution resulting from the separation is designated by F and is obtained as shown on the right-hand side of the channel according to what has been above described in connection to FIG. 7. The thickened solution is discharged from the channel on the right-hand of the partition wall 9, whilst the clarified liquid designated by K is discharged on the left-hand side of the partition wall.

At the inclined channel shown in FIGS. 9-11 the elements corresponding to those in FIG. 8 have been given the same reference characters. By giving the channel an inclined position the force of gravity is utilized at the separation, in addition to the aforementioned effect.

In the embodiment according to FIG. 9 an upper partition wall 10 is arranged. The inlet T in this case is located below the partition wall, the thickened solution F is discharged at the lower end of the channel and the clarified liquid K above the partition wall.

FIG. 10 shows a variant of the embodiment according to FIG. 9 comprising an upper as well as a lower partition wall 11 and 12, respectively. The inlet T is located here as an alternative somewhere along the upper half of the channel and may be, for example, a pipe drawn to this portion. The clarified liquid K can be discharged at the upper end of the channel above the partition wall 11, as shown, or at the lower end of the channel above the partition wall 12.

FIG. 11 shows a further variant comprising a lower partition wall 13, which is curved and together with the web 3 forms a wave-shaped outlet for the thickened solution F, which hereby is compressed. In other respects the embodiment can be in agreement with those shown in FIGS. 9 or 10.

FIG. 12 shows schematically an arrangement according to the invention comprising several channels disposed side by side. The movable channel walls have been formed by a belt 16 drawn between upper rolls l4 and lower rolls l5 and driven with a speed v. For the removal of clarified liquid, the web and/or at least certain rolls can be perforated (not shown). This may be the case also with the webs and rolls comprised in the embodiments according to FIGS. 8-11.

FIG. 13 shows more in detail a part of an apparatus in which the separation effect obtained by the invention is utilized. In a tank 17 a number of channels inclined to the horizontal plane are formed by endless belts 18 (only three are shown) and the walls of the tank. The belts are drawn about upper and lower rolls 19 which in a suitable manner (not shown) are rotatably journalled in two opposite tank walls 20. In the lower part of each channel a partition element 21 is arranged which below and on one side is provided with a suction box 22 having holes 23 on the side facing the abovelying channel part limited by the partition element. The Figure furthermore shows arrows K for clarified liquid obtained by the separation and an arrow F for the obtained thickened solution. The Figure finally also indicates how the particles in the channels surrounding the shown middle belt are in the exemplified case concentrated towards this belt and are discharged between this belt and the partition walls down into the sludge trough 24 of the tank. The clarified liquid K is suctioned through the suction boxes 22 extending out through the tank wall. The inlet for the suspension is not shown in FIG. 13 but can suitably be arranged as an upper inlet. The channel in the apparatus according to FIG. 13 correspond to the channel shown in FIG. 8 disregarding that the channels are inclined to the horizontal.

FIG. 14 shows schematically how an upper inlet T can be arranged to the apparatus according to FIG. 13.

FIG. is, finally, shows schematically how an upper inlet T and upper clarified liquid outlets K in the form of a flow over wear can be arranged at a tank 25 having channels corresponding to the channel illustrated in FIG. 9.

An arrangement according to the invention has a high separation effect. In experiments carried out, for example, with a surface load of 35 m lh liquid feed per m effective separation the following values have been obtained.

Concentration in liquid supplied 2500 mg/litre Concentration in clarified liquid 95 mg/litre The invention, of course, is not restricted to the embodiments described above and shown in the drawing, but it can be varied in several ways within the scope of the following claims. In the embodiments described above with reference to FIGS. 8 to it has been pre supposed that the suspension is supplied at the top of or somewhere along the upper half of the channel. If, however, the density of the particles are essentially heavier than the density of the liquid or lighter than the liquid, it is possible and lies within the scope of the in vention to supply the suspension at the lower end of the channel, wherein the clarified liquid and the thickened solution can be discharged inverted to what has been described above. For stabilizing the flow, furthermore, intermediate discs can be arranged perpendicular to the webs. In the embodiments shown the channel cross section is substantially the same along the extension of the channel. Under certain conditions, however, it can be more advantageous so to design the channel that is is somewhat narrower upwardly than downwardly, or vice versa. In the embodiments shown the channel cross-section is furthermore rectangular (or square). However, the invention is also applicable on channels having other cross-section forms.

We claim:

1. A method for separating suspended or emulsified material from a liquid flowing in a substantially straight channel arranged at an angle with respect to a horizontal plane, the channel being open in both ends and having opposite pairs of side walls, comprising moving at least one of said walls in its longitudinal direction substantially parallel with the axis of the channel in order to create a speed gradient curve having the position of its lowest speed gradient value apart from the axis of the channel, the suspended or emulsified material migrating towards said position of said lowest speed gradient value, and discharging the thus thickened solution and the thus clarified liquid from separate outlets.

2. A method according to claim 1, wherein at least two opposite walls are moving in opposite directions.

3. A method according to claim 2, wherein said walls are moving with different speeds.

4. A method for separating suspended or emulsified material from a liquid flowing in a substantially straight channel arranged at an angle with respect to a horizontal plane, the channel being open in both ends and having opposite pairs of side walls, comprising feeding continuously the suspension or emulsion to one end of the channel, moving at least one of said walls in its longitudinal direction substantially parallel with the axis of the channel in order to create a speed gradient curve having the position of its lowest speed gradient value apart from the axis of the channel, the suspended or emulsified material migrating towards said position of said lowest speed gradient value, and discharging the thus thickened solution and the thus clarified liquid from separate outlets.

5. A method according to claim 4, wherein only on of said walls is moving and in the flow direction of the suspension or emulsion.

6. A method according to claim 5, wherein the spec of said moving wall is about 3/2 times the average speed of the suspension or emulsion.

7. A method according to claim 5, wherein the speed of said moving wall is about 3 times the average speed of the suspension or emulsion.

8. A method according to claim 4, wherein at least two opposite walls are moving in opposite directions.

9. A method according to claim 8, wherein said walls are moving with different speeds.

10. An apparatus for separating material suspended or emulsified in a liquid comprising a substantially straight channel arranged at an angle with respect to a horizontal plane, the channel being open in both ends and having opposite pairs of side walls impervious to said liquid, inlet means for the suspension or emulsion to be separated, means for moving at least one of said walls in its longitudinal direction substantially parallel with the axis of the channel in order to create a speed gradient curve having the position of its lowest speed gradient value apart from the axis of the channel, whereby the suspended or emulsified material migrates towards said position of said lowest speed gradient value, outlet means for discharging the thus thickened solution to a first receptacle means and separate outlet means for discharging the clarified liquid to a second receptacle means.

11. An apparatus according to claim 10, wherein the movable channel wall is a driven endless belt.

12. An apparatus according to claim 10, including dividing means atone end of the channel providing said separate outlet means.

13. An apparatus according to claim 10, said outlet means for the thickened solution is provided at one end of the channel and said separate outlet means for'the clarified liquid is provided at the opposite end of the channel.

14. An apparatus according to claim 13 including dividing means at one end of the channel separating inlet means and outlet means provided at that end.

15. An apparatus for separating material suspended or emulsified in a liquid comprising a plurality of substantially straight channels arranged parallel side by side at an angle with respect to a horizontal plane to form independent separation units, each channel being open in both ends and having opposite pairs of side walls impervious to said liquid, inlet means to each channel for the suspension or emulsion to be separated, means for moving at least one of said walls of each channel in its longitudinal direction substantially parallel with the axis of said channel in order to create in each channel a speed gradient curve having the position of its lowest speed gradient value apart from the axis of said each channel, whereby the suspended or emulsified material migrates towards said position of said lowest speed gradient value, outlet means for discharging from each channel the thus thickened solution to a first receptacle means and separate outlet means for discharging from each channel the clarified liquid to a second receptacle means.

16. An apparatus according to claim 15, wherein each movable channel wall is a driven endless belt. 

2. A method according to claim 1, wherein at least two opposite walls are moving in opposite directions.
 3. A method according to claim 2, wherein said walls are moving with different speeds.
 4. A method for separating suspended or emulsified material from a liquid flowing in a substantially straight channel arranged at an angle with respect to a horizontal plane, the channel being open in both ends and having opposite pairs of side walls, comprising feeding continuously the suspension or emulsion to one end of the channel, moving at least one of said walls in its longitudinal direction substantially parallel with the axis of the channel in order to create a speed gradient curve having the position of its lowest speed gradient value apart from the axis of the channel, the suspended or emulsified material migrating towards said position of said lowest speed gradient value, and discharging the thus thickened solution and the thus clarified liquid from separate outlets.
 5. A method according to claim 4, wherein only one of said walls is moving and in the flow direction of the suspension or emulsion.
 6. A method according to claim 5, wherein the speed of said moving wall is about 3/2 times the average speed of the suspension or emulsion.
 7. A method according to claim 5, wherein the speed of said moving wall is about 3 times the average speed of the suspension or emulsion.
 8. A method according to claim 4, wherein at least two opposite walls are moving in opposite directions.
 9. A method according to claim 8, wherein said walls are moving with different speeds.
 10. An apparatus for separating material suspended or emulsified in a liquid comprising a substantially straight channel arranged at an angle with respect to a horizontal plane, the channel being open in both ends and having opposite pairs of side walls impervious to said liquid, inlet means for the suspension or emulsion to be separated, means for moving at least one of said walls in its longitudinal direction substantially parallel with the axis of the channel in order to create a speed gradient curve having the position of its lowest speed gradient value apart from the axis of the channel, whereby the suspended or emulsified material migrates towards said position of said lowest speed gradient value, outlet means for discharging the thus thickened solution to a first receptacle means and separate outlet means for discharging the clarified liquid to a second receptacle means.
 11. An apparatus according to claim 10, wherein the movable channel wAll is a driven endless belt.
 12. An apparatus according to claim 10, including dividing means at one end of the channel providing said separate outlet means.
 13. An apparatus according to claim 10, said outlet means for the thickened solution is provided at one end of the channel and said separate outlet means for the clarified liquid is provided at the opposite end of the channel.
 14. An apparatus according to claim 13 including dividing means at one end of the channel separating inlet means and outlet means provided at that end.
 15. An apparatus for separating material suspended or emulsified in a liquid comprising a plurality of substantially straight channels arranged parallel side by side at an angle with respect to a horizontal plane to form independent separation units, each channel being open in both ends and having opposite pairs of side walls impervious to said liquid, inlet means to each channel for the suspension or emulsion to be separated, means for moving at least one of said walls of each channel in its longitudinal direction substantially parallel with the axis of said channel in order to create in each channel a speed gradient curve having the position of its lowest speed gradient value apart from the axis of said each channel, whereby the suspended or emulsified material migrates towards said position of said lowest speed gradient value, outlet means for discharging from each channel the thus thickened solution to a first receptacle means and separate outlet means for discharging from each channel the clarified liquid to a second receptacle means.
 16. An apparatus according to claim 15, wherein each movable channel wall is a driven endless belt. 